Organic light emitting diode

ABSTRACT

An organic light emitting diode includes a substrate, a first electrode, an organic functional layer; and a second electrode. One of the first electrode and the second electrode includes a treated patterned carbon nanotube film. The treated patterned carbon nanotube film includes at least two carbon nanotube linear units spaced from each other; and carbon nanotube groups spaced from each other. The carbon nanotube groups are located between the at least two carbon nanotube linear units, and combined with the at least two carbon nanotube linear units.

RELATED APPLICATIONS

This application claims all benefits accruing under 35 U.S.C. §119 fromChina Patent Application No. 201210368134.X, filed on Sep. 28, 2012 inthe China Intellectual Property Office, the disclosure of which isincorporated herein by reference. This application is related to acommonly-assigned application Ser. No. 13/866,408, entitled, “LIGHTEMITTING DIODE,” filed Apr. 19, 2013.

BACKGROUND

1. Technical Field

The present disclosure relates to an organic light emitting diode.

2. Discussion of Related Art

Many organic light emitting diodes (OLED) include a transparentsubstrate, a first electrode (e.g., anode), a second electrode (e.g.,cathode), and an organic light emitting layer located between the firstelectrode the second electrode. The first electrode, organic lightemitting layer, and second electrode are stacked on the transparentsubstrate. The first electrode is in contact with the transparentsubstrate. The second electrode is in contact with the organic lightemitting layer. In an operation, a positive voltage and a negativevoltage are applied respectively to the first electrode and the secondelectrode. Thus, electrons and holes are respectively injected from thefirst and second electrodes into the organic light emitting layer andcombine with each other to emit visible light, and the visible light isemitted out through the first electrode and the transparent substrate.The first electrode should be a transparent material, and is commonlymade of indium tin oxide (ITO). However, the heat generated during theoperation may cause a dispersion of the indium atoms of the ITO into theorganic light emitting layer, which ages the organic light emittinglayer. Further, the ITO has poor mechanical durability, low chemicalendurance, and uneven resistance over its entire area. Thus, the OLEDhas a short life span and is unstable.

What is needed, therefore, is to provide an OLED solving the problemsdiscussed above.

BRIEF DESCRIPTION OF THE DRAWINGS

Many aspects of the embodiments can be better understood with referencesto the following drawings. The components in the drawings are notnecessarily drawn to scale, the emphasis instead being placed uponclearly illustrating the principles of the embodiments. Moreover, in thedrawings, like reference numerals designate corresponding partsthroughout the several views.

FIG. 1 is a schematic view of one embodiment of an OLED.

FIG. 2 is an optical microscope image of one embodiment of a firstelectrode of the OLED.

FIG. 3 is an optical microscope image of another embodiment of the firstelectrode of the OLED.

FIG. 4 is a flowchart of one embodiment of a method for making the firstelectrode of the OLED.

FIG. 5 is a scanning electron microscope (SEM) image of an originalcarbon nanotube film.

FIG. 6 is a schematic view of one embodiment of a patterned carbonnanotube film with through holes substantially arranged in a row.

FIG. 7 is a schematic view of another embodiment of the patterned carbonnanotube film with through holes substantially arranged in a number ofrows.

FIG. 8 is an optical microscope image of the patterned carbon nanotubefilm including through holes.

FIG. 9 is a schematic view of one embodiment of the first electrode ofthe OLED.

FIG. 10 is a schematic view of another embodiment of the first electrodeof the OLED.

FIG. 11 is a schematic view of another embodiment of the OLED.

DETAILED DESCRIPTION

The disclosure is illustrated by way of example and not by way oflimitation in the figures of the accompanying drawings in which likereferences indicate similar elements. It should be noted that referencesto “an” or “one” embodiment in this disclosure are not necessarily tothe same embodiment, and such references mean at least one.

Referring to FIG. 1, one embodiment of an OLED 10 includes a transparentsubstrate 100, a first electrode 110, an organic functional layer 120, asecond electrode 130, and a power source 140. The transparent substrate100 includes a first surface and a second surface opposite to the firstsurface. The first electrode 110, organic functional layer 120, andsecond electrode 130 are stacked on the first surface of the transparentsubstrate 100. The organic functional layer 120 is sandwiched betweenthe first electrode 110 and the second electrode 130. The firstelectrode 110 is in contact with the first surface of the transparentsubstrate 100. The second surface of the transparent substrate 100 is alight emitting surface of the OLED 10. The first electrode 110 andsecond electrode 130 are electrically connected to the power source 140by conducting wires.

The transparent substrate 100 is adapted to support the first electrode110, organic functional layer 120, and second electrode 130. A size,thickness, and shape of the transparent substrate 100 can be selectedaccording to need. A material of the transparent substrate 100 can beglass or plastic.

The first electrode 110 covers the first surface of the transparentsubstrate 100. The first electrode 110 can include a first surface and asecond surface opposite to the first surface. The second surface of thefirst electrode 110 is in contact with the transparent substrate 100.The first surface of the first electrode 110 is away from thetransparent substrate 100, and is not in contact with the transparentsubstrate 100. The first electrode 110 can have a film shape. The firstsurface of the first electrode 110 can be divided into two regions,which are a first region (not labeled) and a second region (not labeled)based on their functions. The first region can be used to have theorganic functional layer 120 located thereon. The second region can beused to have a conducting wire electrically connected thereto. Theconducting wire is electrically insulated from the organic functionallayer 120. In one embodiment, the conducting wire is spaced from theorganic functional layer 120.

A material of the first electrode 110 can be a treated patterned carbonnanotube film 30. Referring to FIG. 2 and FIG. 3, the treated patternedcarbon nanotube film 30 includes a number of carbon nanotube linearunits 32 and a number of carbon nanotube groups 34. The carbon nanotubelinear units 32 and the carbon nanotube groups 34 are connected togetherand located in the same plane to cooperatively form the film shape ofthe treated patterned carbon nanotube film 30. The carbon nanotubelinear units 32 are spaced from each other. The carbon nanotube groups34 join with the carbon nanotube linear units 32 by van der Waals force.The carbon nanotube groups 34 located between adjacent carbon nanotubelinear units 32 are separated from each other.

The carbon nanotube linear units 32 substantially extend along a firstdirection, and are separated from each other along a second directioncrossed with the first direction. A shape of an intersection of eachcarbon nanotube linear unit 32 can be a semi-circle, circle, ellipse,oblate, or other shapes. In one embodiment, the carbon nanotube linearunits 32 are substantially parallel to each other, and distances betweenadjacent carbon nanotube linear units 32 are substantially equal. Thecarbon nanotube linear units 32 are substantially coplanar. A diameterof each carbon nanotube linear unit 32 is larger than or equal to 0.1micrometers, and less than or equal to 100 micrometers. In oneembodiment, the diameter of each carbon nanotube linear unit 32 islarger than or equal to 5 micrometers, and less than or equal to 50micrometers. Distances between adjacent carbon nanotube linear units 32are not limited and can be selected as desired. In one embodiment, thedistances between adjacent carbon nanotube linear units 32 are greaterthan 0.1 millimeters. Diameters of the carbon nanotube linear units 32can be selected as desired. In one embodiment, the diameters of thecarbon nanotube linear units 32 are substantially equal. Each carbonnanotube linear unit 32 includes a number of first carbon nanotubessubstantially extending along the first direction. Adjacent first carbonnanotubes extending along the first direction are joined end to end byVan der Waals attractive force. In one embodiment, an axis of eachcarbon nanotube linear unit 32 is substantially parallel to the axis offirst carbon nanotubes in each carbon nanotube linear unit.

The carbon nanotube groups 34 are separated from each other and combinedwith adjacent carbon nanotube linear units 32 by van der Waals forcealong the second direction. The treated patterned carbon nanotube film30 can be a free-standing structure. The “free-standing structure” meansthat the treated patterned carbon nanotube film 30 can sustain itssheet-shaped structure without any supporter. In one embodiment, thecarbon nanotube groups 34 arranged along the second direction areseparated from each other by the carbon nanotube linear units 32. Thecarbon nanotube groups 34 arranged along the second direction alsoconnect with the carbon nanotube linear units 32.

In one embodiment, the carbon nanotube groups 34 can be staggeredlylocated or disorderly arranged in the second direction. As such, thecarbon nanotube groups 34 in the second direction form non-straightconductive paths in the treated patterned carbon nanotube film 30. Inone embodiment, the carbon nanotube groups 34 are arranged into columnsin the second direction, thus the carbon nanotube groups 34 formconsecutive and straight conductive paths along the second direction inthe treated patterned carbon nanotube film 30. In one embodiment, thecarbon nanotube groups 34 in the treated patterned carbon nanotube film30 are arranged in an array. A length of each carbon nanotube group 34in the second direction is substantially equal to the distance betweenits adjacent carbon nanotube linear units 32, to connect the two carbonnanotube linear units 32 at the two sides of the carbon nanotube group34. The length of each carbon nanotube group 34 on the second directionis greater than 0.1 millimeters. The carbon nanotube groups 34 are alsospaced from each other along the first direction. Spaces betweenadjacent carbon nanotube groups 34 in the first direction are greaterthan or equal to 1 millimeter. The first direction can be substantiallyperpendicular to the second direction.

The carbon nanotube group 34 includes a number of second carbonnanotubes joined together by van der Waals force. Axes of the secondcarbon nanotubes can be substantially parallel to the first direction orthe carbon nanotube linear units 32. The axes of the second carbonnanotubes can also be crossed with the first direction or the carbonnanotube linear units 32. The second carbon nanotubes in each carbonnanotube group 34 can be crossed with each other to form a networkstructure.

The treated patterned carbon nanotube film 30 includes a number ofcarbon nanotubes. The carbon nanotubes form the carbon nanotube linearunits 32 and carbon nanotube groups 34. In one embodiment, the treatedpatterned carbon nanotube film 30 consists of the carbon nanotubes. Thetreated patterned carbon nanotube film 30 defines a number of apertures22′. Specifically, the apertures 22′ are mainly defined by the separatecarbon nanotube linear units 32 and the spaced carbon nanotube groups34. The arrangement of the apertures 22′ is similar to the arrangementof the carbon nanotube groups 34. In the treated patterned carbonnanotube film 30, if the carbon nanotube linear units 32 and the carbonnanotube groups 34 are orderly arranged, the apertures 22′ are alsoorderly arranged. In one embodiment, the carbon nanotube linear units 32and the carbon nanotube groups 34 are substantially arranged as anarray, the apertures 22′ are also arranged as an array. A ratio of anarea sum of the carbon nanotube linear units 32 and the carbon nanotubegroups 34 to an area of the apertures 22′ is less than or equal to 1:19.In other words, in the treated patterned carbon nanotube film 30, aratio of the area having the carbon nanotubes to the area of theapertures 22′ is less than or equal to 1:19. In one embodiment, in thetreated patterned carbon nanotube film 30, the ratio of the total sumarea of the carbon nanotube linear units 32 and the carbon nanotubegroups 34 to the area of the apertures 22′ is less than or equal to1:49. Therefore, a transparency of the treated patterned carbon nanotubefilm 30 is greater than or equal to 95%. In one embodiment, thetransparency of the treated patterned carbon nanotube film 30 is greaterthan or equal to 98%.

The treated patterned carbon nanotube film 30 is an anisotropicconductive film. The carbon nanotube linear units 32 form firstconductive paths along the first direction in the treated patternedcarbon nanotube film 30, as the carbon nanotube linear units 32 extendalong the first direction. The carbon nanotube groups 34 form secondconductive paths along the second direction in the treated patternedcarbon nanotube film 30. Therefore, a resistance of the treatedpatterned carbon nanotube film 30 along the first direction is differentfrom a resistance of the treated patterned carbon nanotube film 30 alongthe second direction. The resistance of the treated patterned carbonnanotube film 30 along the second direction is over 10 times greaterthan the resistance of the treated patterned carbon nanotube film 30along the first direction. In one embodiment, the resistance of thetreated patterned carbon nanotube film 30 along the second direction isover 20 times greater than the resistance of the treated patternedcarbon nanotube film 30 along the first direction. In one embodiment,the resistance of the treated patterned carbon nanotube film 30 alongthe second direction is about 50 times greater than the resistance ofthe treated patterned carbon nanotube film 30 along the first direction.In the treated patterned carbon nanotube film 30, the carbon nanotubelinear units 32 are joined by the carbon nanotube groups 34 on thesecond direction, which makes the treated patterned carbon nanotube film30 strong and stable.

It is noted that there can be a few carbon nanotubes randomlysurrounding the carbon nanotube linear units 32 and the carbon nanotubegroups 34 in the treated patterned carbon nanotube film 30. However,these few carbon nanotubes have a small and negligible effect on theproperties of the treated patterned carbon nanotube film 30.

Referring to FIG. 4, one embodiment of a method for making the treatedpatterned carbon nanotube film 30 includes the following steps:

S10, providing an original carbon nanotube film including a number ofcarbon nanotubes joined end to end by van der Waals attractive force andsubstantially extending along a first direction;

S20, forming a patterned carbon nanotube film 20 by patterning theoriginal carbon nanotube film to define at least one row of throughholes arranged in the original carbon nanotube film along the firstdirection, each row of the through holes including at least two spacedthough holes 22; and

S30, treating the patterned carbon nanotube film 20 with a solvent suchthat the patterned carbon nanotube film 20 is formed into the treatedpatterned carbon nanotube film 30.

Referring to FIG. 5, in step S10, the original carbon nanotube filmincludes a plurality of carbon nanotubes substantially aligned along afirst direction. The original carbon nanotube film can be obtained bydrawing from a carbon nanotube array. Specifically, the original carbonnanotube film can be made by the steps of: providing the carbon nanotubearray including a number of substantially parallel carbon nanotubes; andselecting carbon nanotubes from the carbon nanotube array and pullingthe selected carbon nanotubes substantially along the first direction,thereby forming the original carbon nanotube film.

In one embodiment, the carbon nanotube array is formed on a substrate,and the carbon nanotubes in the carbon nanotube array are substantiallyperpendicular to the substrate. During the pulling process, as theinitial carbon nanotubes are drawn out and separated from the substrate,other carbon nanotubes are also drawn out end to end due to van derWaals force between ends of adjacent carbon nanotubes. This process ofpulling produces the original carbon nanotube film with a certain width.The extending direction of the carbon nanotubes in the original carbonnanotube film is substantially parallel to the pulling direction of theoriginal carbon nanotube film. Therefore, the original carbon nanotubefilm consists of carbon nanotubes, and the carbon nanotubes are combinedby van der Waals force. The original carbon nanotube film is afree-standing structure. The carbon nanotubes in the original carbonnanotube film define a number of micropores, and effective diameters ofthe micropores are less than 100 nanometers.

The step S20 is mainly used to form spaced through holes 22 arrangedalong the first direction in the original carbon nanotube film. Theoriginal carbon nanotube film can be patterned by using laser beams orelectron beams irradiate the original carbon nanotube film.

In one embodiment, the original carbon nanotube film is patterned bylaser beams, and the step S20 includes the following sub-steps. A laseris provided. An irradiating path of a laser beam emitted from the lasercan be controlled by a computer. A shape data of the original carbonnanotube film having the though holes 22 are inputted into the computer,which controls the irradiating path of the laser beam. The laserirradiates the original carbon nanotube film to form the through holes22. A power density of the laser beam ranges from about 10000 watts persquare meter to about 100000 watts per square meter and a moving speedof the laser beam ranges from about 800 millimeters per second (mm/s) toabout 1500 mm/s. In one embodiment, the power density is in a range fromabout 70000 watts per square meter to about 80000 watts per squaremeter, and the moving speed is in a range from about 1000 mm/s to about1200 mm/s.

In step S20, a shape of each through hole 22 can be a circle, ellipse,triangle, polygon, quadrangle, or other shapes. The quadrangle shape canhave at least one pair of parallel sides, such as a parallelogram,trapezia, rectangle, square, or rhombus. In one embodiment, the shape ofeach through hole 22 is rectangular. In another embodiment, the shape ofthe through hole 22 is a straight line, which can be considered as arectangle with a narrow width. A size of the through hole 22 andmicropore represents the maximum distance between one point to anotherpoint both on the edge of the through hole 22 and micropore. Aneffective size of the through hole 22 is larger than the effective sizeof the micropore in the original carbon nanotube film. In oneembodiment, the effective size of the through hole 22 is larger than orequal to 0.1 millimeters. A space between adjacent through holes 22 islarger than the effective size of the micropore in the original carbonnanotube film. In one embodiment, the space between adjacent throughholes 22 is larger than or equal to 0.1 millimeters. The shape andeffective size of the through hole 22 and the space between adjacentthrough holes 22 can be selected as desired. In one embodiment, theshape of the through hole 22 is square having edges larger than or equalto 0.1 millimeters, and the distance between the adjacent through holes22 is larger than or equal to 0.1 millimeters.

In step S20, the patterned carbon nanotube film 20 can be divided into anumber of connecting parts 24 and at least two extending parts 26 by thethrough holes 22. The connecting parts 24 are located between adjacentthrough holes 22 in each row. The connecting parts 24 are separated fromeach other along the first direction by the through holes 22. The atleast two extending parts 26 substantially extend along the firstdirection. The at least two extending parts 26 are connected with eachother on the second direction by the connecting parts 24. Therefore, theat least two extending parts 26 and the connecting parts 24 are anintegrated structure. Specifically, structures of the patterned carbonnanotube film 20 can be described as follow:

(1) Referring to FIG. 6, a number of through holes 22 are separatelyformed in a patterned carbon nanotube film 20. The through holes 22 arearranged into only one row along a first direction X. The firstdirection X is substantially parallel to the extending direction of thecarbon nanotubes in the patterned carbon nanotube film 20. The patternedcarbon nanotube film 20 can be divided into a number of connecting parts24 and two extending parts 26 by the through holes 22. The connectingparts 24 are parts of the patterned carbon nanotube film 20 betweenadjacent through holes 22 in the same row. The two extending parts 26are parts of the patterned carbon nanotube film 20 except the connectingparts 24.

The connecting parts 24 are separated from each other by the thoughholes 22. The connecting parts 24 and the though holes 22 in the samerow are alternately arranged. The two extending parts 26 are located onopposite sides of the connecting parts 24. The extending parts 26 aredivided by the connecting parts 24 along a second direction Y crossedwith the first direction X. In one embodiment, the second direction Y issubstantially perpendicular to the first direction X. Each extendingpart 26 extends along the first direction X.

(2) Referring to FIG. 7 and FIG. 8, a number of through holes 22 arearranged into a number of rows in the patterned carbon nanotube film 20.The through holes 22 in the same row are spaced from each other alongthe first direction X. The through holes 22 in the second direction Yare arranged in columns, and the through holes 22 in the same column arespaced from each other. The through holes 22 can be arranged as anarray. It can be understood that, in another embodiment, the throughholes 22 can also be staggered with each other along the seconddirection Y. That is, the through holes 22 in the second direction Y arenot arranged in a straight line.

The patterned carbon nanotube film 20 is divided into a number ofconnecting parts 24 and a number of extending parts 26 by the throughholes 22. Every adjacent connecting parts 24 in the same row areseparated by the through hole 22. A length of each connecting part 24 isequal to a space between adjacent through holes 22 in the same row alongthe first direction X. Each extending part 26 is a connective structurealong the first direction X. Each extending part 26 is sandwichedbetween adjacent connecting parts 24 in the second direction Y. A widthof each extending part 26 in the second direction Y is equal to a spacebetween adjacent through holes 22 in the second direction Y. Theextending parts 26 connect with adjacent connecting parts 24 arrangedalong the second direction Y. In one embodiment, an effective length ofeach through hole 22 in the first direction X is larger than a spacebetween adjacent through holes 22 along the second direction Y. Theextending parts 26 and the connecting parts 24 are belonged to theintegrated structure of the patterned carbon nanotube film 20.

The shapes of the through holes 22 or the space between adjacent throughholes 22 arranged in the same row or in the same column can bedifferent. In the patterned carbon nanotube film 20, the arrangement ofthe connecting parts 24 is similar to the arrangement of the throughholes 22. There are a few carbon nanotubes protruding around edges ofeach through holes 22, which is a result of the manufacturing process ofthe treated patterned carbon nanotube film 30.

In step S30, the patterned carbon nanotube film 20 is suspended.Referring to FIGS. 2, 3, 8, and 9, the step S30 can include dropping orspraying the solvent on the suspended patterned carbon nanotube film 20,and further shrinking the patterned carbon nanotube film 20 into thetreated patterned carbon nanotube film 30. Because the carbon nanotubesin each extending part of the original carbon nanotube film aresubstantially joined end-to-end and substantially oriented along thefirst direction, and each extending part 26 of the original carbonnanotube film is a consecutive structure on the first direction, theextending parts 26 in the original carbon nanotube film are shrunk intothe carbon nanotube linear units 22 of the treated patterned carbonnanotube film 30 under interfacial tension of the solvent as itdissipates (e.g., volatilizes). During the treating process with thesolvent, each extending part 26 of the patterned carbon nanotube film 20is substantially shrunk toward its center in the second direction andformed into the carbon nanotube linear unit 32, a space between adjacentextending parts 26 will be increased. Therefore, the carbon nanotubelinear units 32 are spaced from each other in the treated patternedcarbon nanotube film 30. A space between adjacent carbon nanotube linearunits 32 in the treated patterned carbon nanotube film 30 is larger thanthe effective diameter of the through holes 22 connected with theextending part 26 or larger than the effective diameter of the throughholes 22 defined in the patterned carbon nanotube film 20 in the seconddirection (e.g., larger than 0.1 millimeters). Simultaneously, eachconnecting part 24 will be pulled along the second direction due to theshrinking of the adjacent extending parts 26. The orientation of thecarbon nanotubes in the connecting part may be varied due to thepulling. The connecting part 24 is formed into the carbon nanotube group34 in the treated patterned carbon nanotube film 30. Therefore, thetreated patterned carbon nanotube film 30 is formed.

An interfacial tension is generated between the patterned carbonnanotube film 20 and the solvent, and the interfacial tension variesdepending on the volatility of the solvent. Pulling forces applied tothe connecting parts 24 are produced by the shrinking of the extendingparts 26. The pulling forces vary depending on the interfacial tension.Different solvent may have different pulling forces to the carbonnanotubes in the patterned carbon nanotube film 20. The pulling forcescan affect the arrangement of the carbon nanotubes in the connectingparts 24, and further affect the structures of the carbon nanotubegroups 34 in the treated patterned carbon nanotube film 30. Differentsolvent may result different arrangement of the carbon nanotubes in thecarbon nanotube groups 34.

Referring to FIG. 2 and FIG. 9, if the solvent is an organic solventwith a high volatility, such as alcohol, methanol, acetone,dichloroethane, or chloroform, the interfacial tension generated betweenthe patterned carbon nanotube film 20 and the solvent is strong. Duringthe process of shrinking the extending parts, pulling forces areproduced. The pulling forces applied to the connecting parts 24 adjacentto the extending parts 26 are strong. The carbon nanotubes orientedalong the first direction in the connecting parts 24 will be formed intothe second carbon nanotubes extending along a direction crossing withthe first direction. Simultaneously, under the interfacial tension, thecarbon nanotubes in each connecting part 24 will be shrunk and eachconnecting part 24 will be formed into the carbon nanotube group 34 witha net structure. In one embodiment, a first angle defined by the secondcarbon nanotubes and the first direction is greater than or equal to 45degrees, and less than or equal to 90 degrees.

In one embodiment, light transmittances of sample 1 (original carbonnanotube film), sample 2 (patterned carbon nanotube film 20), and sample3 (treated patterned carbon nanotube film 30) are tested. In thisembodiment, the patterned carbon nanotube film 20 has a plurality ofthrough holes 22 having the rectangle shape formed by the laser beam.The through holes 22 are arranged in an array. Each through hole 22 hasa length of about 3 millimeters and a width of about 1 millimeter. Adistance between adjacent through holes 22 along the length direction ofthe through holes 22 is about 1 millimeter. A distance between adjacentthrough holes 22 along the width direction of the through holes 22 isabout 1 millimeter. The light transmittances are tested when the samples1-3 are suspended in air. The results are shown in Table 1.

TABLE 1 transmittances to different wavelengths of light/% 370 450 500550 600 650 700 750 sample nm nm nm nm nm nm nm nm 1 76.08 79.17 80.3181.2 81.88 82.46 82.92 83.32 2 80.39 83.03 84.01 84.73 85.27 85.78 86.1486.51 3 98.43 98.42 84.01 98.43 98.40 98.45 98.42 98.38

Referring to FIG. 3 and FIG. 10, if the solvent has a low wetting tocarbon nanotube, such as water in a mixture of water and an organicsolvent, the interfacial force between the patterned carbon nanotubefilm 20 and the solvent is relatively weak. The pulling forces generatedby the shrinking of the extending parts 26 are weak, thus the pullingforces are weakly applied to the connecting parts 24. The arrangementsof the carbon nanotubes in the connecting parts 24 will be a littlechanged by the weak pulling forces. A second angle is defined by thesecond carbon nanotubes in the carbon nanotube groups 34 with the firstdirection. The second angle is less than or equal to 30 degrees. In oneembodiment, the second angle is less than or equal to 15 degrees. In oneembodiment, the first solvent is water, and during the process offorming the carbon nanotube linear units 32, the arrangements of carbonnanotubes in the connecting parts 24 are substantially not changed.Therefore, the second carbon nanotubes in the carbon nanotube groups 34are substantially parallel to the carbon nanotube linear units 32 andthe first direction.

In the step S20, if the through holes 22 are arranged in rows, thecarbon nanotube linear units 32 made from the extending parts 26 of theoriginal carbon nanotube film, will be substantially parallel to eachother. If the through holes 22 are arranged in rows and columns, theextending parts 26 will be formed into carbon nanotube linear units 32substantially extending along the first direction, and the carbonnanotube linear units 32 are separately arranged on the seconddirection. At the same time, the connecting parts 24 will be formed intothe carbon nanotube groups 34, and the carbon nanotube groups 34 willconnect with the carbon nanotube linear units 32 on the second directionand be spaced in the first direction. The carbon nanotube linear units32, which are substantially parallel and separate on the seconddirection, form the first conductive paths substantially extending alongthe first direction. The carbon nanotube groups 34 are connected withthe carbon nanotube linear units 32 in the second directions and spacedin the first direction, which form the second conductive paths extendingalong the second direction.

Therefore, the diameters of the carbon nanotube linear units 32 can beselected by the spaces between adjacent through holes 22 in the seconddirection and the shapes of the through holes 22. Spaces betweenadjacent carbon nanotube linear units 32 can be controlled by the spacesbetween adjacent through holes 22 in the second direction and the widthsof through holes 22 in the second direction. In one embodiment, theshape of the through holes 22 is rectangular, the widths of the throughholes in the second direction are equal, and the spaces between adjacentthough holes 22 in the same rows are equal. Therefore, the shapes andthe diameters of the carbon nanotube linear units 32 are respectivelyequal. Further, if the lengths of the through holes 22 in the firstdirections are equal, the carbon nanotube groups 34 will besubstantially arranged in the second direction and the shapes of thecarbon nanotube groups 34 will be substantially the same. In conclusion,both the spaces between adjacent carbon nanotube linear units 32 and thediameter of the carbon nanotube linear units 32 can be effectively andeasily adjusted according to the method for making the treated patternedcarbon nanotube film 30 provided by the present disclosure.

Under the same condition, a resistance of the treated patterned carbonnanotube film 30 along the first direction is not affected by the numberof the through holes 22 arranged along the first direction. The morethrough holes 22 that are arranged along the first direction, the highera resistance of the treated patterned carbon nanotube film 30 along thesecond direction. The less through holes 22 that are arranged along thefirst direction, the lower the resistance of the treated patternedcarbon nanotube film 30 along the second direction. Under the samecondition, the resistance of the treated patterned carbon nanotube film30 along the second direction is not affected by the number of thethrough holes 22 in the patterned carbon nanotube film 20 along thesecond direction. The more through holes 22 that are arranged along thesecond direction, the higher a resistance of the treated patternedcarbon nanotube film 30 along the first direction. The fewer throughholes 22 that are arranged along the second direction, the lower theresistance of the treated patterned carbon nanotube film 30 along thefirst direction. Therefore, the resistance of the treated patternedcarbon nanotube film 30, especially the electrical anisotropy of thetreated patterned carbon nanotube film 30, can be changed by the numberof the through holes 22 in the patterned carbon nanotube film 20. Thatis, the step S20 can affect the resistance of the treated patternedcarbon nanotube film 30.

It is noted that, the electrical conductivity of the treated patternedcarbon nanotube film 30 can be affected by parameters of the throughholes 22. If the through holes 22 are uniformly distributed in thepatterned carbon nanotube film 20 and each through hole 22 isrectangular, the length of each through hole 22 in the first directionis marked as parameter A, the width of each through hole 22 in thesecond direction is marked as parameter B, the space between adjacentthrough holes 22 in the first direction is marked as parameter C, andthe space between adjacent through holes 22 in the second direction ismarked as parameter D. In one embodiment, the parameter A is smallerthan the parameter D. If compared with the parameter A, the parameter Bis relatively small, the through holes 22 can be considered as straightlines. The affect of the parameters of the through holes 22 on theresistance and electrical anisotropy of the treated patterned carbonnanotube film 30 can be detailed below:

(1) If the parameters A and B are constant, the ratio of the resistanceof the treated patterned carbon nanotube film 30 along the seconddirection to the resistance of the treated patterned carbon nanotubefilm 30 along the first direction is increased as the ratio of theparameter A to parameter B (A/B) increases. The electrical anisotropy ofthe treated patterned carbon nanotube film 30 is proportional to theratio of the parameter A to parameter B.

(2) If the parameters A and C are constant, the resistance of thetreated patterned carbon nanotube film 30 at the first direction isincreased as the ratio of the parameter B to parameter D (B/D)increases.

(3) If the parameters B and D are constant, the resistance of thetreated patterned carbon nanotube film 30 along the second direction isincreased as the ratio of the parameter A to parameter C (A/C)increases. In addition, the electrical anisotropy of the treatedpatterned carbon nanotube film 30 can be improved by decreasing theratio of the parameter A to the parameter C.

In the step S20, the original carbon nanotube film can be suspendedduring the treating by the laser beam and the solvent. The two ends ofthe original carbon nanotube film can be fixed to keep the width of theoriginal carbon nanotube film unchanged. The method for making thetreated patterned carbon nanotube film 30 can further include a step ofcollecting the treated patterned carbon nanotube film 30. Specifically,one end of the original carbon nanotube film drawn from the carbonnanotube array can be fixed on a collecting unit. The collecting unitcan be rotated, the original carbon nanotube film can be continuouslypatterned by the laser beam and treated with the solvent in order, andthen the treated patterned carbon nanotube film 30 is continuouslyformed and collected on the collecting unit.

The organic functional layer 120 is located on the first region of thefirst electrode 110. In one embodiment, a contact area between theorganic functional layer 120 and the first electrode 110 is equal to thefirst region. That is, the first region is entirely covered by theorganic functional layer 120. The organic functional layer 120 includesa hole transporting layer 122, a light emitting layer 124, and anelectron transporting layer 126 stacked in sequence. The holetransporting layer 122 is in contact with and covers the first region ofthe first electrode 110. A material of the hole transporting layer 122has a relatively high electron transport capability, such asN,N′-diphenyl-N,N′-bis(1-naphthyl)-(1,1′-biphenyl)-4,4′-diamine (NPB),N,N′-bis(3-methylphenyl)-N,N′-diphenyl-[1,1-biphenyl]-4,4′-diamine(TPD), or 4,4′,4″-tris(3-methylphenylphenylamino) triphenylamine(MTDATA). A thickness of the hole transporting layer 122 can be chosenaccording to actual need. In one embodiment, the material of the holetransporting layer 122 is NPB.

The hole transporting layer 122 includes a first surface and a secondsurface opposite to the first surface. The second surface of the holetransporting layer 122 is in contact with the first electrode 110. Thelight emitting layer 124 is located on the first surface of the holetransporting layer 122, and spaced from the first electrode 110 by thehole transporting layer 122. In one embodiment, the first surface of thehole transporting layer 122 is entirely covered by the light emittinglayer 124. A material of the light emitting layer 124 has a high quantumefficiency, good semiconducting property, good film forming property,and high thermal stability, and can be a polymer having a largemolecular weight or an organic compound having a small molecular weight.The polymer can have a molecular weight of about 10000 to about 100000.In one embodiment, the polymer can be conducting conjugated polymer orsemiconducting conjugated polymer. The polymer can be formed into a filmby a spin coating method. The small molecular weight organic compoundcan have a molecular weight of about 500 to about 2000, and can beformed into a film by a vacuum deposition method.

The small molecular weight organic compound can be organic dyes havingadvantages such as being highly decorative, large selection available,being easily purified, and having a high quantum efficiency. The smallmolecular weight organic compound can be a red light material, such asone of the rhodamine dyes, DCM, DCT, DCJT, DCJTB, DCJTI, or TPBD. Thesmall molecular weight organic compound can be a green light material,such as coumarin, quinacridone, coronene, or naphthalimide. The smallmolecular weight organic compound can be a blue light material, such asN-aryl-benzimidazole, 1,2,4-triazole derivatives (TAZ), ordistyrylarylene.

The light emitting layer 124 includes a first surface and a secondsurface opposite to the first surface. The second surface of the lightemitting layer 124 is in contact with the hole transporting layer 122.The electron transporting layer 126 is located on the first surface ofthe light emitting layer 124, and spaced from the hole transportinglayer 122 by the light emitting layer 124. In one embodiment, the firstsurface of the light emitting layer 124 is entirely covered by theelectron transporting layer 126. The light emitting layer 124 issandwiched between the electron transporting layer 126 and the holetransporting layer 122. The electron transporting layer 126 has a properelectron transporting capability, a good film forming property, andstability. A material of the electron transporting layer 126 can be anaromatic compound having a relatively large conjugated surface, such astris(8-hydroxyquinolino)aluminum (Alq3),2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (PBD),bis(hydroxybenzoquinolinato) beryllium (BeQ₂), or4,4′-bis(2,2′-diphenylvinyl)-1,1′-biphenyl (DPVBi). The electrontransporting layer 126 can also be used as a light emitting layer 124.

The electron transporting layer 126 includes a first surface and asecond surface opposite to the first surface. The second surface is incontact with the light emitting layer 124. The second electrode 130 islocated on the first surface of the electron transporting layer 126. Inone embodiment, the first surface of the electron transporting layer 126is entirely covered by the second electrode 130. The second electrode130 is electrically connected to the power source 140 by a conducingwire. The second electrode 130 can be a layer structure. A material ofthe second electrode 130 is metal or alloy. In one embodiment, thematerial of the second electrode can be a metal with a low workfunction, such as lithium, magnesium, calcium, strontium, aluminum, andindium, or an alloy having copper, gold, or silver alloyed with a lowwork function metal. In one embodiment, the material of the secondelectrode 130 is an Mg—Ag alloy. The thickness of the second electrode130 can be selected according to actual need.

Further, the second electrode 130 has a first surface and a secondsurface opposite to the first surface. The second surface of the secondelectrode 130 is in contact with the electron transporting layer 126. Areflector layer (not shown) can be located on the first surface of thesecond electrode 130. A material of the reflector layer can be titanium,silver, aluminum, nickel, gold or a combination thereof. The reflectorlayer includes a smooth surface having a high reflectivity. The photonsthat reach the reflector layer can be reflected by the reflector layer,thus, these photons can be extracted from the OLED 10 through the secondsurface of the substrate 100 to improve light extraction efficiency ofthe OLED 10.

In one embodiment, a buffer layer (not shown) can be disposed betweenthe first electrode 110 and the hole transporting layer 122. The bufferlayer can decrease the lattice mismatch between the first electrode 110and the hole transporting layer 122, to increase the stability of theOLED 10. A thickness of the buffer layer can be less than 10 nanometers.A material of the buffer layer can be polymethylmethacrylate, polyimide,fluoropolymer, LiF, AlF₃, CaF₃, MgF₂, SiO₂, MgO, Al₂O₃, or diamond.

In use, a voltage is applied between the first electrode 110 and thesecond electrode 130. Thus, holes and electrons enter the organicfunctional layer 120 and combine with each other to emit visible light,and the visible light is emitted from the transparent structure.

Referring to FIG. 11, another embodiment of an OLED 40 is provided. TheOLED 40 includes a substrate 400, a first electrode 410, an organicfunctional layer 120, a second electrode 430, and a power source 440.The first electrode 410, organic functional layer 120, and secondelectrode 430 are stacked on the first surface of the substrate 400. Theorganic functional layer 120 is sandwiched between the first electrode410 and the second electrode 430. The first electrode 410 is in contactwith the first surface of the substrate 400. The first electrode 410 andsecond electrode 430 are electrically connected to the power source 440by conducting wires.

The OLED 40 of the second embodiment is similar to the OLED 10 of thefirst embodiment. The difference is that the first surface of the secondelectrode 430 is a light emitting surface of the OLED 40. The secondelectrode 430 is transparent. In one embodiment, the second electrode430 is a transparent film, such as the patterned treated carbon nanotubefilm 30. The substrate 400 and the first electrode 410 can both beopaque. In one embodiment, the first electrode 210 is made from an Mg—Agalloy.

Further, a reflector layer (not shown) can be located between the firstelectrode 410 and the substrate 400. The reflector layer includes asmooth surface having high reflectivity. The photons that reach thereflector layer can be reflected by the reflector layer, thus, thesephotons can be extracted from the OLED 40 through second electrode 430to improve the light extraction efficiency of the OLED 40.

The treated patterned carbon nanotube film has high conductivity, isstable, and is used as the electrode of the OLED to increase the workingcurrent and life span of the OLED. The light transmittance of thetreated patterned carbon nanotube film is high (e.g., about 95%), thus,the OLED has good transparency and high light extraction efficiency. Inthe treated patterned carbon nanotube film, each of the carbon nanotubelinear units and the carbon nanotube groups are formed from a pluralityof carbon nanotubes closely combined with each other by van der Waalsattractive force, which makes the treated patterned carbon nanotube filmhave better mechanical properties than the original carbon nanotube filmand the patterned carbon nanotube film. The mechanical durability of theOLED can be improved. A ratio of a total area of the plurality of carbonnanotube linear units and the plurality of carbon nanotube groups to atotal area of the plurality of apertures can be less than or equal to1:19. Thus, when the treated patterned carbon nanotube film is locatedon the organic functional layer, the contacting area between the treatedpatterned carbon nanotube film and the organic functional layer can bedecreased, to decrease the affect of the carbon nanotubes on the organicfunctional layer.

It is to be understood that the above-described embodiment is intendedto illustrate rather than limit the disclosure. Variations may be madeto the embodiment without departing from the spirit of the disclosure asclaimed. The above-described embodiments are intended to illustrate thescope of the disclosure and not restricted to the scope of thedisclosure.

It is also to be understood that the above description and the claimsdrawn to a method may include some indication in reference to certainsteps. However, the indication used is only to be viewed foridentification purposes and not as a suggestion as to an order for thesteps.

What is claimed is:
 1. An organic light emitting diode comprising: asubstrate; a first electrode; an organic functional layer; and a secondelectrode; wherein the first electrode, the organic functional layer,and the second electrode are stacked on the substrate, the firstelectrode is in contact with the substrate, one of the first electrodeand the second electrode comprises a treated patterned carbon nanotubefilm, and the treated patterned carbon nanotube film comprises: at leasttwo carbon nanotube linear units spaced from each other, and a distancebetween the at least two carbon nanotube linear units is greater than0.1 millimeters; and a plurality of carbon nanotube groups spaced fromeach other, located between the at least two carbon nanotube linearunits, and combined with the at least two carbon nanotube linear units.2. The organic light emitting diode of claim 1, wherein the at least twocarbon nanotube linear units are substantially parallel to each otherand are aligned along a first direction to form first conductive paths.3. The organic light emitting diode of claim 2, wherein the plurality ofcarbon nanotube groups are spaced from each other in the first directionand are combined with the at least two carbon nanotube linear units in asecond direction, that intersects with the first direction, to formsecond conductive paths; and the first conductive paths intersect withthe second conductive paths.
 4. The organic light emitting diode ofclaim 3, wherein the at least two carbon nanotube linear units comprisea plurality of carbon nanotube linear units, the plurality of carbonnanotube groups are located between each of two adjacent carbon nanotubelinear units and are arranged in a staggered manner in the seconddirection.
 5. The organic light emitting diode of claim 3, wherein theat least two carbon nanotube linear units comprise a plurality of carbonnanotube linear units, the plurality of carbon nanotube groups arelocated between each of two adjacent carbon nanotube linear units andare arranged in columns in the second direction.
 6. The organic lightemitting diode of claim 1, wherein each carbon nanotube linear unitcomprises a plurality of carbon nanotubes joined end-to-end by van derWaals force and substantially oriented along an axis direction of theeach carbon nanotube linear unit.
 7. The organic light emitting diode ofclaim 1, wherein a diameter of each carbon nanotube linear unit isgreater than or equal to 0.1 micrometers, and less than or equal to 100micrometers.
 8. The organic light emitting diode of claim 1, whereineach carbon nanotube group comprises a plurality of carbon nanotubessubstantially extending along an axis direction of the at least twocarbon nanotube linear units.
 9. The organic light emitting diode ofclaim 1, wherein each carbon nanotube group comprises a plurality ofcarbon nanotubes that intersect an axis direction of the at least twocarbon nanotube linear units.
 10. The organic light emitting diode ofclaim 1, wherein a distance between adjacent carbon nanotube groupslocated between the at least two carbon nanotube linear units is largerthan 1 millimeter.
 11. The organic light emitting diode of claim 1,wherein the first electrode comprises the treated patterned carbonnanotube film, and the substrate is a transparent substrate.
 12. Anorganic light emitting diode comprising: a substrate; a first electrode;an organic functional layer; and a second electrode; wherein the firstelectrode, the organic functional layer, and the second electrode arestacked on the substrate, the first electrode is in contact with thesubstrate, one of the first electrode and the second electrode comprisesa treated patterned carbon nanotube film, and the treated patternedcarbon nanotube film comprises: a plurality of carbon nanotube linearunits spaced from each other; and a plurality of carbon nanotube groupsspaced from each other and combined with the plurality of carbonnanotube linear units, wherein the plurality of carbon nanotube linearunits and the plurality of carbon nanotube groups cooperatively define aplurality of apertures, a ratio of a total area of the plurality ofcarbon nanotube linear units and the plurality of carbon nanotube groupsto a total area of the plurality of apertures is less than or equal to1:19.
 13. The organic light emitting diode of claim 12, wherein theratio is less than or equal to 1:49.
 14. The organic light emittingdiode of claim 12, wherein the plurality of carbon nanotube linear unitsare substantially parallel to each other and are aligned along a firstdirection.
 15. The organic light emitting diode of claim 14, wherein theplurality of carbon nanotube groups are spaced from each other in thefirst direction and are combined with at least two carbon nanotubelinear units in a second direction, and the first direction isperpendicular to the second direction.
 16. The organic light emittingdiode of claim 14, wherein each carbon nanotube group comprises aplurality of carbon nanotubes substantially extending along the firstdirection.
 17. The organic light emitting diode of claim 14, whereineach carbon nanotube group comprises a plurality of carbon nanotubesintersected with the first direction.
 18. An organic light emittingdiode comprising: a substrate; a first electrode; an organic functionallayer; and a second electrode; wherein the first electrode, the organicfunctional layer, and the second electrode are stacked on the substrate,the first electrode is in contact with the substrate, one of the firstelectrode and the second electrode comprises a treated patterned carbonnanotube film, and the treated patterned carbon nanotube film comprises:at least two carbon nanotube linear units spaced from each other; and aplurality of carbon nanotube groups spaced from each other, locatedbetween the at least two carbon nanotube linear units, and combined withthe at least two carbon nanotube linear units, and a distance betweenadjacent carbon nanotube groups located between the at least two carbonnanotube linear units is greater than 1 millimeter.